Lesson objective: Solve systems of equations by using a graph.

This lesson helps to build procedural skill with graphing and solving systems of equations. A graph is used here because it supports a visual understanding of a solution to a system of equation. This work develops students' understanding that a point of intersection is an ordered pair that makes both equations true in a system of equations.

Students engage in Mathematical Practice 4 (model with mathematics) as they model a system of equations with a graph or use the graph of a system of equations to identify a solution.

**Key vocabulary:**

- coinciding
- infinitely many
- intersection
- ordered pair
- parallel
- slope
- y-intercept

**Special materials needed:**

- Graph paper and/or graphing technology